Animating materials for blinking effect
It's hacky, and annoying if you want to use it for its intended purpose, but you can animate (or drive) the Pass Index of an object, and access it through an Object Info Input node.

Using a setup like this..



In this example, the Pass Index of each object is animated cyclically, with step-wise interpolation, from 0 to 4. This can yield an sequence like the one below..



..with all the objects sharing the same material, and their cyclic Pass Index animations offset in the dope sheet.



Following stav's suggestion of a rearrangement, here's a version in which the Pass Index is not animated, but used to set the phase: the number of frames a color cycle is offset for the object bearing it. (See comments)



The 'Frame No.' and 'Cycle Period' nodes are both Input > Value nodes, with the value in  'Frame No.' keyframed with a linear interpolation to match the frame number of the animation. The Color Ramp will be swept in the number of frames in the 'Period' node. In this case, the Pass indices of the groups of objects are 0,4 and 8, to get a trailing 1-on, 2-off effect.